K.L.
When our impulses and feelings shift a bit, we often blame the relationship when it could be something simply physiological. There is something we experience as mothers of young children that few of us understand.
Our children touch us a lot. They need to. Touch is the first language a child understands. When a young child is not touched often, they feel there is no communication, as if they are living in solitary confinement. Whether we know it or not, our hands and the touch of the child next to our body speaks volumes to the child.
But, there is a metabolic backlash in the mother's body from all that touch, because our bodies are also responding to all that touch.
When the body perceives a nurturing, protective, giving and caring touch, that body produces an increase in hormone and neuro-peptides that are nurturing, protective, and supportive to us. However, when the touch we receive is perceived as a taking or demanding touch, the body produces stress hormones. Those stress hormones are not conducive to a healthy libido.
However gentlemanly a man may be, if his body is wanting something, his touch communicates want and your body may have had it's limit of anyone's body expecting something from your body.
Because women become mothers, they more often tend to naturally develop the ability to give that selfless and nurturing touch. Some men are better at learning this than others. Can he give you a nurturing massage without becoming aroused? If not, can you find a good massage therapist to give you the kind of touch you need to help your body get its nurture and stress hormones back in balance?
So, before you go blaming the endurance of your relationship, you might explain all this to your husband and find ways to experiment with healing, balancing, and nurturing touch to see if things don't improve. I think of this sort of touch as pre-foreplay. But, this touch needs time to have it's effect. So, if you are given a nice healthy massage when he first comes home in the evening, you might be feeling a bit more sexual after the children are in bed.